Radio signaling system



May 1;192s. v 1,667,792

' DE LOSS K. MARTIN RADIO S IGNALING SYSTEM Filed Jan. 11, 1923 mamecal-re Plum INVENTQR Patented May l, 1928.

UNITED .STATES PATENT OFFICE.-

. DE Loss n MARTIN, or onANGa'NEW-Jnnsnx, AssieNon To .aMERicA'NTELEPHONE y AND TELEGRAPH COMPANY, A CORPORATION or NEW Yonx.

RADIO SIGNALING SYSTEM.

This invention .relates to radio signaling.

` Campbell, Serial No. 327,553, dated September 30, 1919. By the properspacing of the separate antenna structures constituting such an arrayand by the proper phasing of the currntsimpressed upon or received bysuch antenna structures, the directional characteristic of'suchstructures for transmitting and receiving may be controlled. Bysuchcontrol we may effect maximum radiation or reception in a singledirection or in two directions, either diametrically o posite lor at amore acute angle toeach ot er, or we may eiect simultaneous vradiationin many directions. v These, however, are by no means the only ways inwhich radiation from an' antenna array may be controlled but are simplyillustrative of the directional iiexibil-v ity of an antenna array.

My invention consists in the utilization of this inherent characteristicof' an antenna `oarray to effect the transmission of telegraph ortelephone signals between two or more stationsfconstituting a system.

- This invention will be better understood from the followingdescription when read in connection with the attached drawing, of

Y which Figure 1 shows schematically two sta.-

tions, each having an antenna array by means of which the method inwhich my invention is embodied may be carried out, Figs. 2 and 2 showdirectional characteristics of a stem in which my invention is embodied,ment for a station adapted to'transmit telegra h signals in accordancewith the princip es of my invention and Fig. 4 shows the circuitarrangement for a station adapted to transmit telephone signals.

In Fig. 1, A represents .a transmitting station and B a receivingstation, each havty of separatefa'ntenna structures, a at ig. 3 showsthe circuit arrange- .B depen irigian antennaarray, represented by aplul shown the use of an antenna array at the receiving station, itshould be understood that an antenna array is not necessary at thereceiving station in order to carry out the invention since an type ofreceiving antenna may used. lllloreover, the invention .is not limitedto an antenna arra. of a particular type but may be embodied in any typeof an arrayin which the directional characteristic may be readilychanged by varying the phase angle of the currents ap.- plied to theseparate antenna structures whereby the direction of radiation oftheentire array may be readily changed. For the purpose of describing theprinciple of my invention the characteristic of the array shown at thetransmitting station A of Fig.

l is that represented by the solid line cli'arn acteristic of Fig. 2.'This characteristic designated a shows maximum radiation toward theright, and the zone'of radiationV is rather narrow. There is also acertain amount lof radiation, but' a relatively small amount, which isrepresented by the otherv solid line Aloois which radiate from the Ifthe axial point o this characteristic. transmitting station A vnormallytransmits alongthe line 1, the array .connected with 'thev receivingstation B will vbe aiected thereby tothe maximum degree, assuming,

ofcourse,`that the individual antenna structures at stationB are solocated and the phase controllingapparatus connected with the individualantenna and with the common receiving circuit are likewise so ad-V ofthe radiated wave is along the line 2 or 3, the antenna arra at stationB would be affected to a lesser egree than if the transmission had beenalong the line 1 and, by Y controlling the radiation characteristic, the

effect upon the station B may made substantial y nil. From the foregoingbrief de.

scription, it will be seen that the degree of receptiviy of the antennaarray at station s radiation o f the ener from station A.

I employ this principle for the transmission of telegraph signals bdirecting a high frequency `impulse along t line 1 to repreupon thedirection of maximum v sent the transmission of a marking signal and Ialter the direction of radiation, that is to say, I direct-it along thelines 2 or 3 to represent a spacing signal. The form of the radiationcharacteristic, and the direction of-propagation for the marking and theThus, 'in Fig. 2a' the `characteristic of the marking signal. designateda is similar to that shown in Fig. 2. In order to send a spacing signal,the radiation characteristic is changed so as to eectively suppressradiation along the line 1, whereby substantially no energy reachesthedistant receiving station along this line. This is shown by thedotted line characteristic designated b which shows substantially equalradiation in four directions but in which the amount of radiation in anydirection is Avery small.

Having in mind the basic principle under which signals may betransmitted to a distant receiving station either by changing the line tof direction of transmission of the antenna array as shown in Fig. 2 orby changing the directional characteristic of the array as shown in Fig.2, I `will now proceed to describe two transmitting cirlcuits embodyingthe foregoing principles,

one of which, Fig. 3, shows the means for transmitting telegraph signalsand the other of which, Fig. 4., shows means for transmitting telephonesignals.

In Fig. 3, X1, X2, X3 and Xn represent a plurality of antennastructuresspaced at a definitempuart of a wave Vlength apart and, taken together,constitutingthe antenna array. Connected with each of the said antennaeis a power am liier designated A1, A2, Aa and' An. ile these poweramplifiers may be of any well known type it would probably be desirableto use the Iyvell known thermionic vacuum tube ampliers.

f. amptlifier's through a plurality of phase shi ing devices, PS2, PS2,PS3 and PSn is a source of high frequency current O, which Connectedwith each of the said the condensers-has a definite impedance Z.;

at the frequency of the current generated by the source O. Each of thesaid phase shifting devices has associated therewith supplementalcondensers designated C3 and C4', in connection with PS1,which normallyare lnot connected effectively into the circuit of the network.

High frequency oscillations will be impressed by the conductors 3 and 4upon the conductors 13 and Maand will be radiated by'the antenna X1; andin similar manner oscillations will be impressed upon the conductors l5and 16, 17 and 18 and 19 and 20 and radiated by the antennae X2, X3 and`Xn. Assuming that-the key K is open, the phase angle which theseoscillations will have when applied to the respective antennae willbe'determinedby the impedance Z2 of the networks PS2, PS2, PS3 and PSD,individual to their respective antennae. Let it ybe assumed that these'oscillations are phased in suc-l1 a manner that the direction ofradiation is represented by the dotted line charac'teristic b of Fig.2'. This represents the transmission of aspacing signal to the distantreceiving station, since theI amount of energy received there may bemade practically nil by making the angle 9 suiiciently large. In orderto transmit a' marking signal, the key K isclosed, which in turnoperates the relays R1 and R2 of phase shifter PS1 by the iow of currentfrom the battery B over conductors 2 'and 6, relays R1 and R2,conductors 5 and 1 and through the key K. 'In similar manner, otherrelays connected with the phase Shifters PS2, PS3

and PSu would be controlled by the current from the battery B. Theoperation of relays R1 and R2 effectively connects into the network ofthe phase shifter PS1 theV condensers C2 and C2', which changes thephase angle of the-current flowing from the source O to the antenna X1because the impedance of the net work is changed from Z to Z. In hkemanner, although not necessarily to the same degree, the phase angle ofthe current owing from the -same'source to the other antennae of thearray would be changed so that the directional characteristic of thearray would be represented by a of Fig. 2. 'Huis results, therefore, inthe transmission of n marking signal to the distant receiving station.

In carrying outl the method of operating -llU r he direction of the ofFig. 2a, but,

this circuit in the Fig. 2, the amount of radiation in any direction ispractically signal is being transmitted, while, on the ot er hand, theradiation is a maximum in receiving station when a marking signal is tobe transmitted. This may be .effected in the arrangement shown in Fig. 3by the proper adjustment of the networks'of the various phase Shiftersto produce substantial neutralization of radiation whenthe key K is openas shown by b on the other hand, to effect maximum radiation along apredetermined line, as represented by a of Fig. 2, when amarking signalis to be transmitted.

The arrangement for transmitting telephone signals is showniin Fig. 4.,in which the same reference numerals or letters as are of all of thesedevices,

used in Fig.. 3 represent similar parts. In

this figure, a type of antenna array similar to that shown in Fig. 3 isused. Each antenna of the array has connected therewith a poweramplifier which is connected through a phase shifter with a. source ofhigh frequency current O. The phase shifter differs structurally, atleast, from that shown in Fig. 3. Y Phase shifter PS1, which is typicalcomprises a plurality ofiron core inductance coils, .of which certain ofthe windings are connected with the high frequency source and otherwindings are connected with the low frequencyncrophone M, having Thehigh frequency L4 have,connected therewith condensers C1, C2, C, and C4,

which togetherv constitutea network having a deinite impedance Zo at thefrequency of the source O, provided the permeability of theiron coresremains fixed. The phase anle of the current supplied to the antennagil, for example, may be changed-by varying the ermeability of the ironcores. This may be one by actuating the microphone M,

which varies the ilow' of current from the battery B over a circuitcomprising conductors` 1 and 5,' windings Le, L5, L9, L7 and L8 andconductors 6 and 2. It will be readily seen that the permeability of theiron-cores-upon which the various windings are placed will be varied inaccordance with the voice currents resulting from the actuation of themii ances which results inl substantially mmer crophone M. Thesevariations of the permeability of these cores will result in changingthe value of the high frequency induct diate changes in the.l phaseangle ofthe high frequency currentsl applied to the 1 antenna X1. Itwill, -of course, be apparent that while these changes in the phaseangle are occurring in the current applied to e antenna X1, similarchanges occurl in the cur- -rents applied to the other antenna, byvirtue of the operations of the phase Shifters PS2,

manner represented by nil when a spacingA voice Waves are imp ingi-ngupon the microa direct current source B connected therewith. windingsL11, L2, L3 land circuit is shown in Fig. 12 of the said Aappli- PS3 andPSD. If the phase Shifters are sov adjusted that when no variations oftheidirect Acurrent circuit are occurring, the phase cordance with thechanges in the direct curi rent circuit resulting fromthe voice waves.It will be apparent, therefore, that at a distant receiving station suchas B of Fig. 1, having an antenna array which is adjusted to givemaximum receptivity along the linev 1, the' receptivity would vary inaccordance with variations of the 'angle 0 representing the deviation ofthe radiation characteristic from this line, that is to say, the amountofcurrent received at B would vary in accord- -ance with 'the voicewaves impressed upon the microphone M. It will be accordingly seen thatthe radiation characteristic va. of

Fig. 2 which represents the normal radiation o the antenna array of Fig.4, when no pl1one M, may be shifted in accordance with `the volce wavesimpressed upon the said'microphone so that the angle 0 which thelongitudinal axis of the characteristic a makes with vthe line `joiningthe transmitting and the receiving stations line 1 of Fig. 1, will varyin accordance with variations of the voice waves.

lWhile no mention has been made'heretoy lfore of the arrangement of thereceiving circuit of this system, it is to be understood that any wellknown type of receiving antenna may be used. If it be desired to use anan tenna array at the receiving station, such a cation of George A.Campbell, Serial No.` 327,533. It employs a plurality of antennee spaceda definite part of a wave length apart and having connected therewithand individual thereto a each havin and phase s ifting devices, whichcircuits are connected with a common receiving circuit` having asuitable local-source of high frequency oscillationsfor the4 detectionof the 120 lowfrequency signals. While this invention has been `describeas embodied .in a paiticular form and arrangement of parts iris to'beunderstood i that it is capable of embodiment in other and 125di'erent'form within the spirit and scope of the appended claims. Y fWhat is claimed is: l 1. In a vradio signaling system having atransmitting station comprising a transmit- 180 ico as, for example,the.4

plurality of circuits, the necessary filters, ampliiiers ting antennaarray, Aa source of high frequency current, and signaling means forcontrolling the vdlrectional characteristic of the said array connectedtherewith, and a .re

i trolling the directional characteristic of the said. array connectedtherewith, and a receiving station having receiving apparatus connectedtherewith, the method of signaling which consists in varying themagnitude of radiation in a given direction only by and in accordancewith the signals being. transmitted.

3. In a .radio signaling system havinga transmitting station comprisinga. transmitting antenna array, a source of high frequency current, andsignaling means for controlling the directional characteristic of thesaid array connected therewith, and a. receiving station havingreceiving apparatus connected therewith, the method of signaling whichconsists in producing maximum radiation in a given direction only toeffect the transmission of one type of signal and to produce substantialsuppression of radiation to effect the transmission of a different typeof signal.

4. In a radio signaling system haying a transmitting station comprisinga transmitting antenna. array, a source of high frequency current, andsignaling means for controlling the directional characteristic of thesaid array connected therewith, and a receiving station having receivingapparatus connected therewith, the method 0f signalving which consists.in varying the phase of the high frequency currents by and inaccordance with the signals being transmitted,

whereby the directional characteristic of the array maybe varied.

5. In a radio signaling system comprising a'transmittin station and a`receiving station', each having an antenna array arranged forunilateral transmission and reception therebetween, the degree ofreceptivity varying with the changes in the directional chari acteristicof the transmitting array, the method of signaling which consists inproducing such a directional characteristic' of the transmitted-wave asto eii'ect maximum receptivity and varying the directionalcharacteristic to vary the degree of receptivity by and in accordancewith `the signals being tennae, means individual to each antenna tocontrol the phase of the current supplied thereto by the said commonsource of current, and means to simultaneously change the phase of thecurrent supplied to each antenna whereby the array is caused t0 have adifferent dlrectional characterlstic.

'7. In a radio signalingsystem, the combih nation with an antenna arraycomprising a` plurality of antennae substantially equally spaced apart,of a source of high frequency .currentcommon to the said antennae, aphase shifter individual to each antenna and connected between the saidsource and each antenna, a source of signalsalso common to said antenna,and switching means individual t0 each phase shifter and controlled bysaid source of signals to change the constants of the saidzphase shifterwhereby the phase angleof the currents supplied to the .antennae ischanged and the axis of the beam. of energy radiated by the said arrayis shifted.

In testimony whereof, I have signed my- Vname to this specification this10th day of- January, 1923.

, IniLossicMARTIN.-l

